INCORPORATION BY REFERENCE: Applicant(s) hereby incorporate herein by reference, any and all U.S. patents, U.S. patent applications, and other documents and printed matter cited or referred to in this application.
1. Field of the Invention
This invention relates generally to an apparatus and method for music production by at least two remotely located musicians, and more particularly to a stereo telephone device providing an interactive audio mixing board and expandable bandwidth.
2. Description of Related Art
The following art defines the present state of this field:
Lee, U.S. Pat. No. 4,130,734 describes an analog bandwidth compressor of the present system preserves the actual frequencies of the detected signal. This is accomplished by feeding the detected signal to a bank of contiguous filters and feeding the outputs of each of these filters to an AM detector and a frequency divider. The output from each frequency divider is fed to a tunable filter bank. The outputs of the tunable filter bank are fed to multipliers where the outputs from the associated AM detectors are superimposed on the frequency signals from the tunable filter bank. The output of the plurality of multipliers is fed to a summing network which provides a reduced bandwidth signal. The output of the summing network is subsequently fed through a transmission system to a bandwidth restoration circuit which consists of a tunable contiguous filter bank, AM detector, frequency multiplier, tunable filter bank, multipliers and a summer similar to the bandwidth reduction circuit.
Hoque et al, U.S. Pat. No. 4,922,536 describes in-studio, stage or field applications, high fidelity audio signals are transmitted to a remote processor in digital form in order to solve the problems of audio degradation, cross talk, ground loops and multi-cable problems associated with the analog transmission of multiple channels of audio over long distances. In one embodiment a TDM/FDM multiplexing system is utilized with increased bandwidth and dynamic range compared to data and telephone multiplexing systems to accommodate high fidelity requirements. In an embodiment involving a distributed system, multiple MUX and DEMUX modules are coupled in a distributive fashion along a light-weight transmission line, in which each of the modules is assigned a predetermined transmission frequency and with each of the modules having a number of audio inputs which are time-multiplexed for that particular MUX module and frequency. The Subject System precludes the necessity of running multiple audio cables to remote destinations, while at the same time providing an exceptionally quiet system, since the digital data stream is extremely tolerant to cross talk, ground loops, noise, signal attenuation, and non-linearity associated with conventional analog audio transmission.
Brotz et al, U.S. Pat. No. 5,020,101 describes a musician""s telephone interface that interconnects an instant location through a telephone line to a remote location such device having inputs to receive the sound from musical instruments and/or vocalization at each location with balancing circuitry and broadcast means at each location for the musicians at each location to hear the music of one another simultaneously balanced for collaboration and production of music.
Nakano et al, U.S. Pat. No. 5,182,768 describes a digital telephone set connected to a digital data exchange through a transmission line. A plurality of handsets, which are mounted on a telephone body, are for converting input sounds into input analog speech signals and for converting output analog speech signals into output sounds. Connected to the handsets, a plurality of analog-to-digital converters converts the input analog speech signals into input digital speech signals. Connected to the handsets, a plurality of digital-to-analog converters converts output digital speech signals into the output analog speech signals. On the telephone body are mounted a set of dialing keys for producing a numerical signal. Connected to the dialing keys, a control device is for producing input control data in response to the numerical signal and is for producing an output control signal in response to output control data. Connected to the transmission line, the control device, the analog-to-digital converters, and the digital-to-analog converters, a multiplexing/demultiplexing circuit is for transmitting/receiving transmission/reception time division multiplexed signals to/from the digital data exchange through the transmission line. The multiplexing/demultiplexing circuit is for multiplexing the input digital speech signals and the input control data into the transmission time division multiplexed signal and for demultiplexing the reception time division multiplexed signal into the output digital speech signals and the output control data.
Brotz et al, U.S. Pat. No. 5,398,278 describes a telephone interface system to interconnect the output of two or more musicians, one at an instant location and the other at a remote location, over communication lines, such system converting the analog musical output to digital form for duplexing over the communication lines.
Usami, U.S. Pat. No. 5,572,561 teaches a frequency dividing circuit including a first inverter circuit supplied with a first frequency-divided signal, a second inverter circuit supplied with a second frequency-divided signal which has a complementary relationship to the first frequency-divided signal, and a first pair of push-pull circuits. There are also provided a first switch circuit performing a first switching operation in response to a first input signal and selectively supplying output signals of the first and second inverter circuits to the first pair of push-pull circuits so that one of the first pair of push-pull circuits performs a pull-up operation when the other one thereof performs a pull-down operation. Further, there are provided a second pair of push-pull circuits, and a second switch circuit performing a second switching operation in response to a second input signal which has a complementary relationship to the first input signal and selectively supplying output signals of the first pair of push-pull circuits to the second pair of push-pull circuits so that one of the second pair of push-pull circuits performs a pull-up operation when the other one thereof performs a pull-down operation. The first and second frequency-divided signals are output from the second pair of push-pull circuits.
MacDonald, U.S. Pat. No. 5,587,673 teaches a circuit (10) for generating an output signal having a frequency that is a multiple of an input clock signal (CLKIN). The circuit includes a delay circuit (12) having an input port and a plurality of output ports (A, B, C). The input port is coupled during use to the input clock signal. Individual ones of the plurality of output ports output a signal that is delayed with respect to the input clock signal and also with respect to others of the plurality of output ports. The circuit further includes a logic network (20) having a first input for coupling to the input clock signal and a plurality of second inputs for coupling to the plurality of output ports. The logic network operates to logically combine signals emanating from the plurality of output ports with the input clock signal, and has an output port (OUTPUT) for outputting a signal having a frequency that is multiple of a frequency of the input clock signal. The signal that is output from the output port of the logic network has a 50% duty cycle regardless of the duty cycle of the input clock signal.
Marchand, U.S. Pat. No. 5,680,067 teaches a frequency dividing device having an input terminal for a signal to be divided and an output terminal for an output signal. It further comprises: a first mixing circuit which is particularly of the sub-harmonic type, has a first input which forms the input terminal, and a second input for receiving a signal from a local oscillator; a first dividing circuit for dividing the output signal of the first mixing circuit; a second dividing circuit for dividing the output signal of the local oscillator; and a second mixing circuit which has a first input for receiving the output signal of the first dividing circuit, and a second input for receiving the output signal of the second dividing circuit, and an output which forms the output terminal.
Hirata, U.S. Pat. No. 5,703,509 describes a frequency multiplier circuit that needs no coupling capacitors and no input bias circuits for a next-stage circuit, which includes a phase-shifted signal generator, first and second differential amplifiers, and a multiplier. The phase-shifted signal generator receives an initial input signal and generates first and second output signals whose phases are shifted by 90.degree. with each other. The first differential amplifier amplifies the first output signal to output a first positive-phase output signal and a first negative-phase output signal. The second differential amplifier amplifies the second output signal to output a second positive-phase output signal and a second negative-phase output signal. The multiplier multiplies the first and second positive-phase output signals to output a third positive-phase output signal as a positive-phase output of the frequency multiplier circuit. At the same time, it multiplies the first and second negative-phase output signals to output a third negative-phase output signal as a negative-phase output of the frequency multiplier circuit. Each of the third positive- and negative-phase output signals has a doubled frequency of the initial input signal and substantially the same dc offset voltage.
Simons et al, U.S. Pat. No. 5,914,620 describes a method and system of frequency multiplying a signal having amplitude modulation using a frequency multiplier operated at a bias voltage that is less than its saturation mode voltage is described. Prior to amplification, the amplitude modulated signal is pre-distorted to compensate for distortion caused by the frequency multiplier. A first pre-distortion phase converts the amplitude modulated signal into a corresponding square root signal to compensate for a first distortion type. A second pre-distortion phase pre-distorts the square root signal to compensate for the distortion caused by biasing the frequency multiplier at a voltage less than the saturation voltage of the multiplier. As a result, a signal that is amplitude modulated can be multiplied by a frequency multiplier.
Reichard et al, U.S. Pat. No. 5,999,618 teaches a telephone interface system for the transmission and reproduction of an audio performance, particularly a musical performance, at separate locations utilizing an amplitude modulated carrier frequency. The system serves to both transmit a performance at one instant location to one or more remote locations and to receive and reproduce a similar performance from the remote locations transmitted to the instant location. The performers at all locations hear the audio output of the performances at the other locations as though such other performers were actually present.
McClellan, (December, 1999) Test Equipment For Audio Technicians: Balanced-Line Converter, Electronics Now, pp. 41-44, describes a balanced Line Converter that offers a simple solution to the balanced line conversion problem. The unit accepts unbalanced inputs from consumer audio gear and has balanced outputs with impedances and levels that are suitable for professional audio equipment. The input impedance is 100,000 ohms-suitable for all solid state equipment and most vacuum tube gear. The latter is especially desirable if you use tube type microphone preamplifiers or signal processors. Such devices are currently popular in recording studios.
Szabo, (February 1993) Audio Level Controler, Electronics Now, pp. 41-44, describes a programmable audio-level controller to control the receiver""s input and keep it in a comfortable zone.
Cypress Semiconductor Corporation, (Jan. 5, 2000), Frequency Multiplier and Zero Delay Buffer, San Jose, Calif., describes a two-output zero delay buffer and frequency multiplier. It provides an external feedback path allowing maximum flexibility when implementing the Zero Delay feature.
Burr-Brown Corration, (December 1995), Wide Bandwidth Precision Analog Multiplier, Tucson, Ariz., describes a wide bandwidth, high accuracy, four-quadrant analog multiplier. Its accurately laser trimmed multiplier characteristics make it easy to use in a wide variety of applications with a minimum of external parts, often eliminating all external trimming. Its differential X, Y, and Z inputs allow configuration as a multiplier, squarer, divider, square-rooter, and other functions while maintaining high accuracy.
Burr-Brown Corporation, (March 1995), Multiplier-Divider, Tucson, Ariz., describes a multiplier-divider having a low cost precision device designed for general purpose application. In addition to four-quadrant multiplication, it also performs analog square root and division without the bother of external amplifiers or potentiometers. Laser trimmed one-chip design offers the most in highly reliable operation with guaranteed accuracies. Because of the internal reference and pretrimmed accuracies the MPYlOO does not have the restrictions of other low cost multipliers. It is available in both TO-100 and DIP ceramic packages.
Burr-Brown Corporation, (August 1993), Voltage-to-Frequency and Frequency-to Voltage Converter, Tucson, Ariz., describes a monolithic voltage-to-frequency and frequency-to-voltage converter that provides a simple low cost method of converting analog signals into digital pulses. The digital output is an open collector and the digital pulse train repetition rate is proportional to the amplitude of the analog input voltage. Output pulses are compatible with TTL, and CMOS logic families.
Burr-Brown Corporation, (October 1993), Wide Bandwidth Signal Multiplier, Tucson, Ariz., describes a wide-bandwidth four-quadrant signal multiplier. Its output voltage is equal to the algebraic product of the X and Y input voltages. For signals up to 30 MHz, the on-board output op amp provides the complete multiplication function with a low-impedance voltage output. Differential current outputs extend multiplier bandwidth to 75 MHz.
The prior art teaches various apparatuses which convert analog signals to digital and the reverse, as well as allowing multiplexing over phone lines. The prior art also teaches a multiplexing system with increased bandwidth and dynamic range, where a transmission occurs over lightweight coaxial cable, or fiberoptic or twisted-pair cable. However, the prior art does not teach an invention and method that allows transmission of signals between local and remote musicians where the transmission occurs over standard phone lines with a bandwidth of up to 20 kHz, which is nearly seven times that enabled by prior art technology. The present invention fulfills these needs and provides further related advantages as described in the following summary.
The present invention teaches certain benefits in construction and use which give rise to the objectives described below. The present invention is an apparatus and method for joint music production from a remotely separated plurality of musicians joined by phone lines of a public telephone system. The public telephone system has a signal frequency cutoff limiting transmission to a low range which is incompatible with music. Each of the musicians produces a local music signal (MSL) with full audio range. This signal is impressed on the public telephone system which creates a low-end outbound music signal (LEL). Also, separately, the MSL signal is filtered through a first high-pass filter and mixed with a mixer signal to produce a sum/difference signal (SDL). The SDL signal is impressed onto the second phone line of the public telephone system as a high-end outbound music signal (HEL). A second mixer circuit receives at least one remotely produced sum/difference signal (SDR) and the mixer signal and this is again filtered to obtain the high end signal only (HER). The HER signal and the at least one remotely produced low-end signal (LER) are summed to produce the remotely originated limited band pass music signal (MSR). TMSL and the MSR signals are summed for listening to the joint music production. Brotz et al, U.S. Pat. No. 5,398,278 teaches the use of conversion to digital form for multiplexing over a transmission line, while, Brotz et al, U.S. Pat. No. 5,020,101 describes a musician""s telephone interface that interconnects an instant location through a telephone line to a remote location; such device having inputs to receive the sound from musical instruments and/or vocalization at each location with balancing circuitry and broadcast means at each location for the musicians at each location to hear the music of one another simultaneously balanced for collaboration and production of music. Reichard et al teaches transmission of an audio signal using an amplitude modulated carrier signal. The instant invention does not use modulation or multiplexing so that it clearly distinguishes over these references, and Reichard et al is not considered prior art in that its priority date is subsequent to the reduction to practice of the instant invention. It is also noted that a provisional application filed Dec. 30, 1998 set priority of the parent application to which this CIP is a continuation.
A primary objective of the present invention is to provide an apparatus and method for music production by at least two remotely located musicians having advantages not taught by the prior art.
Another objective is to provide such a apparatus and method of use, which is able to be utilized by musicians using conventional phone lines.
A further objective is to provide such an apparatus and method of use which allows a signal of up to 20 kHz bandwidth, which provides a band pass of nearly seven times that which is able to be conveyed over standard phone lines.
Other features and advantages of the present invention will become apparent from the following more detailed description, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention.